Aspects of the present invention are directed to a nanowire field effect transistor (FET) and, more particularly, to a nanowire FET with a metal gate that is surrounded with silicide around the metal gate for inducing radial and, in some cases, longitudinal strain in the nanowire channel.
In a field effect transistor (FET) with nanowire channels, it is possible to induce longitudinal strain in the nanowires since the relatively small diameters of the nanowires leads to efficient strain coupling from a stressor. While longitudinal strain was studied in detail in planar devices and more recently longitudinal tensile strain was demonstrated with nanowire FETs, the effect of radial strain on the carrier transport in nanowires is unknown.
One of the main challenges with studying the impact of radial strain in a nanowire FET is that the gate material needs to be varied to change the strain level. Altering the gate conductor changes the induced strain but also other properties of the device such as the work function. Additionally, the use of different gate materials requires substantial processing development.